Transgenic crops

Modifying the genetic make-up of a plant can improve crop yields or resistance to pests

Since the first genetically modified (GM) crops went on sale in 1996, areas planted with these crops have increased by around 3–4 per cent a year and in 2014 covered at least 1.8 million square kilometres, an area roughly twice the size of France.

GM crops may be controversial – because they contain DNA that has been modified by humans adding DNA from other species – but they hold the potential to solve many of the problems facing modern agriculture, such as the rapidly changing climate and soaring human population. Genetic engineering can not only improve crop yields more rapidly than traditional crop-breeding techniques but also alter crops by introducing genes from completely unrelated species, such as bacteria, to create transgenic plants.

Crops already approved for use in the USA include soy modified to be more tolerant to the weedkiller glyphosate and pest-resistant maize, known as Bt corn, that kills rootworm. Bt corn includes a gene from the bacteriumBacillus thuringiensis which allows it to produce a toxin that kills the rootworm. It now makes up 75 per cent of maize harvested in the USA. However, the continued use of Bt is threatened by rootworm populations that have adapted to resist the toxin. In the state of Iowa, resistance is already rife.

The next generation of GM crops may be plants with altered levels of nutritional components such as oils, proteins and starch, or with increased resistance to drought or salt. These types of crops are already being tested in field trials. But GM crops aren’t embraced everywhere: Scotland announced plans to ban the growing of GM crops in 2015.

Lead image:

Rootworm damage on maize roots.

New York State IPM Program at Cornell University/Flickr –
Photo: Keith Waldron
CC BY NC ND

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